The invention is an air type solar collector with a highly absorptive radiation absorber. The absorber is constructed in three dimensions. Instead of attempts at increasing the depth of a surface as attempts have been made with flat plate absorbers, my absorber has depth built in. Instead of passing the conducting air against one or both sides of known absorbers; in this invention, air passes through an interstitial body that has tissue which may be comprised of great numbers of fibrous cylindrical surfaces like but not limited to small sized fibers having a collective surface area several times the surface area of a flat plate including its fins if so equipped. Thus, its depth and great surface area provide for high efficiency in the essential critical requirements and properties desirable in a solar collector absorber.
The collector's first cost is low because it is simple and easy to manufacture and contains economical materials. It is lightweight because of its simplicity and porous structure. Its great absorber surface area results in corresponding ability to absorb solar radiation, and efficiently conserve heat losses because the heated fibers are in close proximity to other fibers of like temperature and insulated by distance from unlike structures and temperatures.
The absorber material such as fibers may be selected for low cost and absorbing qualities. It may, when necessary, receive selective coatings for increased radiation absorption, relative position fixing and durability. They may have a cross-sectional size as small as rock-wool or metal wools like fine steel wool. The fibers are fixed to cohere in irregular arrangement relative to each other. They are separated by air from each other to the extent practical to provide a three dimensional absorber perforated to the extent that substantially all the solar energy transmitted by the transpatent cover penetrates the absorber in depth, for good air passage as the conducting fluid, yet close enough to provide sufficient mass within a practical absorber depth for blanketing and absorbing essentially all the solar radiation penetrating the absorber. When necessary the fibers are fixed in position with high thermal adhesive.
The depth or thickness of the absorber may exceed ten centimeters for the ordinary house collector. Design depth is determined by the distance between the cool and warm air ducts, distance between fibers, type of operation such as passive flow or active flow, and whether a reflector is used behind the absorber mass. Fiber mass may be decreased when a reflective shield is located behind the absorber. The reflector may act as a partial substitute for depth or density, or both as it reflects scattered and spurious radiation back to the fibers bypassed.
The absorber is disposed between a transparent cover of highly acceptable critical properties for solar collecting and an insulation shield when a reflector is not used. About the insulation, a container is fitted to provide rigidity to the collector parts and for mounting the collector to other collectors, their duct works and to a parent support.
The collector air ducts connect to the larger absorber air ducts in any manner desired. The absorber ducts may vary in shape depending on type of transparent cover, the thickness or depth of the absorber, or the presence of a reflective shield, for varying air recovery speeds within the absorber, and for slowing recovery adjacent the cover to decrease conduction.
Slowing of rate of air recovery adjacent a transparent cover of single glazing is desirable; however, when the cover is insulated as with double glazing, the absorber ducts may be shaped to increase the recovery rate adjacent the cover. Increased flow adjacent the cover is efficient when heavy fiber density is used with double glazing.
Air enters at the cool air ducts located at the bottom of the collector, replaces the air between the fibers that has been warmed by them and exits via the warm air ducts located at the top of the collector.
As long as the heighth of the collector is kept within operating limits, the collector may easily be made in several shapes and dimensions. One or several collectors may be used to frame a window or a door. Thus, it may substitute for exterior wall or roof coverings or the complete wall while providing good absorbing performance even in vertical walls and at angles not perpendicular to the sun. Reinforced, it could serve as the walls and roof of a building. It may be priced low enough to be employed at angles and tilts whereby it can be utilized only part of each day.